Impact of Molecular Pathology on Classifying Diffuse Gliomas
Impact of Molecular Pathology on Classifying Diffuse Gliomas
The traditional categorization of gliomas into their morphological subgroups (astrocytic, oligodendroglial, and ependymal) typically precedes textbook discussions of particular entities. This is likely to change. In a seminal, genome-wide study, Parsons et al documented IDH1 mutations in subsets of glial neoplasms. It was soon recognized that mutations of IDH1 are frequent in FAs, ODs, and MOAs, particularly at amino acid residue 132 (arginine), which is replaced by histidine in nearly 90% of tumors bearing an IDH1 mutation. This residue may also be replaced by cysteine, serine, or other amino acids, and mutations may rarely occur at other loci. IDH2 may also be affected, albeit at a different locus (residue 172). Mutations of other IDH isoforms have not been reported to accompany gliomagenesis. Thus, the finding of an IDH1 or IDH2 mutation can be termed IDH-mut, and the absence of a mutation in either gene is designated as IDH wild type (wt). Acute myeloid leukemia, chondrosarcoma, and giant cell tumor of the bone may also exhibit IDH mutations.
Two Groups of Gliomas
The traditional categorization of gliomas into their morphological subgroups (astrocytic, oligodendroglial, and ependymal) typically precedes textbook discussions of particular entities. This is likely to change. In a seminal, genome-wide study, Parsons et al documented IDH1 mutations in subsets of glial neoplasms. It was soon recognized that mutations of IDH1 are frequent in FAs, ODs, and MOAs, particularly at amino acid residue 132 (arginine), which is replaced by histidine in nearly 90% of tumors bearing an IDH1 mutation. This residue may also be replaced by cysteine, serine, or other amino acids, and mutations may rarely occur at other loci. IDH2 may also be affected, albeit at a different locus (residue 172). Mutations of other IDH isoforms have not been reported to accompany gliomagenesis. Thus, the finding of an IDH1 or IDH2 mutation can be termed IDH-mut, and the absence of a mutation in either gene is designated as IDH wild type (wt). Acute myeloid leukemia, chondrosarcoma, and giant cell tumor of the bone may also exhibit IDH mutations.
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